21788

Appears in sequences

• a(n) = 1*t(n) + 2*t(n-1) + ...+ k*t(n+1-k), where k=floor((n+1)/2) and t is A001950 (upper Wythoff sequence).at n=44A023867
• Smallest k > 0 with gcd(k, rev(k)) = n, where rev(k) is digit reversal of k, or 0 if no such k exists.at n=51A069554
• If p(x) is the x-th prime, then the n-th set of 4 consecutive sexy prime pairs starts at p(a(n)).at n=30A095963
• G.f. satisfies: A(x) = 1 + x*A(x)^2 + 2*x^2*(A(x)^2 - A(x)); equals the base sequence of pendular trinomial triangle A122445.at n=9A122446
• The number of unigraphical partitions of 2m; that is, the number of partitions of 2m which are realizable as the degree sequence of one and only one graph (where loops are not allowed but multiple edges are allowed).at n=36A143981
• a(n) gives the number of nonisomorphic connected compact Lie groups of dimension n which are simple products.at n=56A177821
• Column 3 of array in A226513.at n=25A226514
• Values of n such that prime(n) does not divide any 10-digit pandigital number (i.e. any value in A050278).at n=5A292703